first aid high sierra volume could not be unmounted

However the option to delete the BOOTCAMP partition is disabled in Disk Utility. So what I thought I could try is delete my BOOTCAMP partition, which is about 100GB, and then merge the free space into the problem partition so that I can run fsck -fy in single user mode to try to repair the volume which now will have enough space to complete the operation. Now the disk is greyed out in disk utility and I can't reinstall mac os x because I would need to erase all of the data on the drive and I don't want to lose the files I have on it. Sorry I didn't get any screenshots or anything but that is basically what happened. (I had about 13GB of free space at this time) Then it tried to restore the disk to it's original state on mount but it couldn't do this either, I'm guessing because of lack of disk space.

So I opened in recovery mode and ran the first aid and it tried to fix the B-Tree of the catalog file, however there wasn't enough disk space to do this.

I was trying to repair permissions today on my Mac so I ran the Disk Utility's First Aid on my drive and it said that there was an Invalid Index Key and that my disk was corrupt and I needed to run the first aid in Recovery mode.

First aid high sierra volume could not be unmounted